The use of the colonoscope for examining the interior of the large intestine or colon is well-known. In general, a physician performing an examination or treatment of the colon inserts a colonoscope into the anus and then advances the colonoscope into the colon. A complete examination requires the physician to advance the colonoscope into the colon, negotiate the sigmoid colon, and left and right colic flexures up to the cecum. Advancement of the colonoscope is generally accomplished by manipulation of a steerable tip of the colonoscope, which is controlled at the proximal end of the device by the physician, in addition to torquing and pushing the scope forward or pulling it backward.
Problems regularly occur, however, when negotiating the colonoscope through the bends of the colon, such as at the sigmoid and left and right colic flexures. These problems arise because the colon is soft and has unpredictable fixation points to the viscera of the abdomen, and it is easily distensible. Consequently, after the steerable tip of the colonoscope is deflected to enter a new region of the colon, the principal direction of the force applied by the physician urging the proximal end of the device into the patient's colon is not in the direction of the steerable tip. Instead, the force is directed along the axis of the colonoscope towards the preceding bend(s), and causes yielding or displacement of the colon wall.
The loads imposed by the colonoscope on the colon wall can have a myriad of possible effects, ranging from patient discomfort to spastic cramp-like contractions of the colon and even possible perforation or dissection of the colon. Consequently, the colonoscope cannot be advanced as far as the cecum in up to one-sixth of all cases.
To address some of these difficulties, it is known to employ a guide tube that permits a colonoscope to be advanced through the rectum. One such device is described in U.S. Pat. No. 5,779,624 to Chang. An alternative approach calls for inserting the colonoscope through a curved region, and then mechanically actuating the portion of the device in the curved region to cause it to straighten, as described in U.S. Pat. No. 4,601,283 to Chikama.
Many patients find the operation of such previously-known devices unpleasant because the sigmoid portion of the colon is forced into an almost rectilinear shape by the guide tube. Due to the stiffness of the guide tube, careless handling of the guide tube presents a risk of injury to the colon.
Other previously-known apparatus and methods use an overtube having variable rigidity, so that the overtube may be inserted through curved anatomy in a flexible state, and then selectively stiffened to resist bending forces generated by passing a colonoscope through the overtube. One example of such a device is described in U.S. Pat. No. 5,337,733 to Bauerfiend. The device described in that patent comprises inner and outer walls having opposing ribs spaced apart across an air-filled annulus. The ribs are selectively drawn together to intermesh, and form a rigid structure by evacuating the annulus.
Another previously-known endoscopic device for delivering aneurysm clips within a hollow organ or vessel is described in U.S. Pat. No. 5,174,276 to Crockard. The device described in that patent includes a conduit formed from a multiplicity of elements that are capable of angulation relative to one another, and which becomes rigid when subjected to a tensile force. The device is described as being particularly useful in neurosurgery, where the variable rigidity of the device is useful for providing a stable platform for neurosurgical interventions, such as clipping an aneurysm.
While previously-known apparatus and methods provide some suggestions for solving the difficulties encountered in advancing diagnostic or therapeutic instruments through easily distensible body organs, few devices are commercially available. Although the precise reasons for this lack of success are uncertain, previously-known devices appear to pose several problems.
For example, the devices described in the Bauerfiend and Crockard patents appear to pose a risk of capturing or pinching tissue between the endoscope/colonoscope and the distal end of the overtube or conduit when the scope is translated. Also, neither device provides any degree of steerability, and must be advanced along the pre-positioned scope. In addition, the bulk of the proximal tensioning system described in Crockard is expected to interfere with manipulation of the endoscope. Other drawbacks of previously-known devices may be related to the complexity or cost of such devices or the lack of suitable materials. In any event, there exists an un-met need for devices to solve this long-felt problem in the field of endoscopy and colonoscopy.
In view of the foregoing, it would be desirable to provide apparatus and methods for facilitating placement of diagnostic or therapeutic instruments within easily distensible hollow body organs, such as the esophagus or colon.
It further would be desirable to provide apparatus and methods that permit a diagnostic or therapeutic device to be advanced into a hollow body organ, and which facilitates passage of the device through tortuous anatomy without requiring straightening of organ passageways already traversed.
It also would be desirable to provide apparatus and methods for facilitating placement of diagnostic or therapeutic instruments within easily distensible hollow body organs that include means for reducing the risk that tissue will become inadvertently pinched between the sheath apparatus and the advancing or withdrawing instrument, or caught as the diagnostic or therapeutic instrument is maneuvered through the hollow body organ.
It still further would be desirable to provide apparatus and methods that provide a low-cost, single use, easily manufacturable guide for inserting a diagnostic or therapeutic instrument in a hollow body organ.
It yet further would be desirable to provide apparatus and methods that provide a low-cost, easily manufacturable guide for inserting a diagnostic or therapeutic instrument in a hollow body organ, wherein a portion of the apparatus is disposable after a single use and a remaining portion of the device is re-usable.
Still further, it would be desirable to provide a device having a selectively locking shape for inserting a diagnostic or therapeutic instrument in a hollow body organ, but which facilitates manipulation of a proximal end of the diagnostic or therapeutic instrument.
It additionally would be desirable to permit multiple diagnostic or therapeutic devices to be positioned in a hollow, unsupported organ, so that at least one of the devices may be withdrawn and repositioned while the other devices are retained in place.